An Edwardian yacht in deep space races around the planets. There is a double agent in the TARDIS crew. The White Guardian warns the Fifth Doctor of great danger. Turlough must finally choose sides and at the end of the race lies the prize of Enlightenment.
The Doctor
Tegan Jovanka
Vislor Turlough
The White Guardian
The Black Guardian
Striker
Marriner
Wrack
Mansell
First Officer
Jackson
Collier
